Overhead opening plug door

ABSTRACT

An overhead opening plug door for a pressurized aircraft cabin wherein the door is counterbalanced for manual emergency opening in event of power failure, yet the door is easily closed and sealed in normal operation. Power actuated cables move the door, which is roller mounted on tracks of nonconstant curvature, by means of push-pull rods and cam linkages into open and closed position.

United States Patent inventors Kenneth Ritchie Malibu; LeonardSchroedter, La Palma, both of, Calif. Appl. No. 838,949 Filed July 3,1969 Patented June 22, 1971 Assignee McDonnell Douglas CorporationOVERHEAD OPENING PLUG DOOR 8 Claims, 9 Drawing Figs.

Int. Cl E05d 15/20 Field of Search 49/208- [56] References Cited UNITEDSTATES PATENTS 2,587,863 3/1952 Lambert 49/216 X 3,440,762 4/1969 OlssonL Primary Examiner-Kenneth Downey Attorneys-Walter 1. Jason, Donald L.Royer and Robert 0.

Richardson ABSTRACT: An overhead opening plug door for a pressurizedaircraft cabin wherein the door is counterbalanced for manual emergencyopening in event of power failure, yet the door is easily closed andsealed in normal operation. Power actuated cables move the door, whichis roller mounted on tracks of nonconstant curvature, by means ofpush-pull rods and cam linkages into open and closed position.

OVERHEAD OPENING PLUG DOOR BACKGROUND OF THE INVENTION In aircraftcapable of high-altitude flights the cabin is pressurized for thecomfort of the passengers. This subjects the inner faces of the cabindoors to air pressure loads. Obviously, if a door were constructed toopen outwardly and the door latch were inadvertently released in flight,the-air-pressure differential would cause the door to fly open inmidair. To preclude the occurrence of such an accident, doors of aplugin-type are used. One such door is described in U.S. Pat. No.3,085,297 issuing Apr. 16, I963 to Hal R. Linderfelt for Door forPressurized Cabin." The structure of this door required it to moveinwardly, pivot, and then swing outwardly to fully open position. Theplug door of the present invention, however, is of the overhead openingtype to avoid a requirement of door hinge clearance.

Vertically moving doors of the type comprising the present invention areheavy and require power assistance in moving them upwardly. In event ofpower failure they must be manually operable to open. Usually strongcounterbalance springs assist in this operation. However, to close andseal the door requires considerable effort in opposition to thesesprings.

SUMMARY OF PRESENT INVENTION The overhead opening plug door comprisingthe present invention has rollers for movement along nonconstantcurvature tracks which impart an inward and upward direction to the dooras it is opened by power-actuated cables. Cam linkage between the cablesand the rollers on the door cause the door to be moved into and from itssealed closed position at a minimum expenditure of force and energy. Thestress and strain on the fuselage structure is not transmitted to thedoor structure because of its looseness of fit yet the door iseffectively sealed and retained in its closed position in flight.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side view of an aircraftshowing the approximate location of ingress and egress doors;

FIG. 2 is a perspective view with portions broken away showing a door inoverhead position over the door entranceway;

FIG. 3 is a schematic illustration showing the cable and linkage whichactuates the door;

FIGS. 4 and 5 are elevational views of alternate embodiments partly insection to show the linkage structure and the door in several positions;

FIG. 6 is a perspective view of the upper rollers, bellcrank and upperend of the push-pull rod;

FIGS. 7 and 8 are perspective views of alternate forms of lower rollersand linkages; and

FIG. 9 is an elevational view showing the cable actuating mechanism.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Referring now to FIG. 1 there isshown a side view of a commercial transport aircraft 10 having a pair ofengines 12 mounted on wings 14. A third engine 16 is mounted on the tailsection 18. The fuselage 20 has four access passenger doors 22, 24, 26and 28 on each side, for a total of eight doors. The latter six doorsare of the same contour and are identical except for local mechanismadjustment and the two forward doors, because of the aircraftconfiguration, will be leftrighthand construction.

Door 24 is illustrative of the rest and is shown in FIG. 2 in its raisedposition above door jamb 30. Tracks 32 of nonconstant curvature extendupwardly on both sides of the door opening and are adapted to receiverollers 34 which are attached to the door 24 to carry it between itsopen and closed positions. Motor 36 mounted to rotate shaft 38 is thepower source for moving a cable 40 which, in turn, moves the door eitherup or down. Counterbalance springs 42 oppose the weight of door 24 tofacilitate manual movement of the door to open position when necessary.As can be observed from the eight-across seating and the size of thefuselage, the door 24 appears to be large and heavy.

In FIG. 3 there is shown the door 24 having an upper support shaft 44and lower support shaft 46 rotatably mounted and extending horizontallyfrom the sides of the door. Affixed to each end of shaft 44 is abellcrank 48 having rollers 50 on long arm 52 to engage a track, notshown. These rollers are mounted on a roller support 54 pivotallymounted on arm 52 of bellcrank 48. Continuous cable 40 is attached tothe roller support 52 and constitutes the power means for moving thedoor 24 up and down. Cable 40 extends over pulleys 56, 58 and over apower drum 60 which is actuated by motor 36 to move the door.

The short arm 62 of bellcrank 48 is connected to lower bellcrank 64 by apush-pull rod 66. This bellcrank 64 is mounted on lower shaft 46 withthe push-pull rod 66 attached to the short arm 68 of the bellcrank. Inthe illustration in FIG. 3 the bellcrank 64 has a pair of long arms 70with roller supports 72 pivotally mounted thereon. Each support 72 hasrollers 74 which engage door jamb tracks, not shown.

In operation in moving door 24 upwardly the motor 36 exerts an upwardpull on cable 40. This causes bellcrank 48 to rotate clockwise in FIG. 3until shaft 44 is in line with the direction of pull on cable 40. Thismoves the top of the door inwardly somewhat but not enough to clear theupper header 76 of the door opening. This also places an initial tensionon push-pull rod 66, imparting a counterclockwise rotation on arm 68 oflower bellcrank 64. This in turn will cause rollers 74 v to react on thetrackway, not shown, to cause the door to move inwardly prior to itsupward movement.

Continued upward force on cable 40 causes more reaction of the rollers74 and translates the tension on push-pull rod 66 into compressionbecause the rod tends to move upwardly faster than the upper bellcrank48. This imparts further rotation on the bellcrank and thus camming theupper portion of door 24 further inwardly prior to vertical movement.Thereafter further pull on the cable 40 moves the door to its overheadposition.

In the lowering of the door 24 the reverse action takes place. The motor36 pulls the cable 40 downwardly in opposition to the action of thecounterbalance springs 42. The door then moves downwardly with the aidof gravity (the doors weigh approximately 300 pounds) and is not allowedto oscillate due to the configuration of the lower bellcrank in thefour-bar linkage system on the door. As the lower bellcrank 64approaches the lower end of the track, not shown, rotation of thebellcrank is induced by the lower track curvature, causing the lower endof the door to close into the door opening. This rotation appliestension on push-pull rod 66, which in turn rotates upper bellcrank 48clockwise about its support 54 at the end of long arm 52. This moves theupper part of the door into the door opening.

The sectional views in FIG. 4 and FIG. 5 show alternate embodiments oflinkage structure for operation in the manner just described. Briefly,the upper and lower bellcranks are reversed and the physicalconstruction of the lower bellcranks differ. In FIG. 4 there is shown adoor opening between the top door jamb 76 and the bottom 78. Door 24 isshown in its closed position with the rollers 74 on lower bellcrank 64at the bottom of track curvature 80. Tracks 82 extend upwardly on bothsides of the door jamb with a nonconstant curvature, providing a camsurface for the bellcranks 48 and 64 to move the door 24 inwardly whenit is pulled upwardly. Bellcranks 48 and 64 carry door 24 by pivotshafts 44 and 46 and are connected by push-pull rod 66 as shown. As thedoor is pulled upwardly it first moves inwardly to the position shown byphantom line 24A. In this position the push-pull rod is shown as 66A,lower bellcrank as 64A and upper bellcrank as 48A. The doors uppermostposition is shown as 248. In lifting the door 24 in FIG. 4 the force onpush-pull rod 66 is converted from compression to tension whereas in theembodiment shown in FIG. 5 the force is converted from tension tocompression.

Before describing the embodiment in FIG. 5, reference is had to thebellcranks 48 in FIG. 6 and 64 in FIG. 7. These bellcranks are used inthe embodiment shown in FIG. 4. In FIG. 6 there is shown bellcrank 48mounted on the top pivoting shaft 44. This bellcrank has a short arm 62connected to the top end of push-pull rod 66. A longer arm 52 extendsangularly from the short arm and has a roller support 54 pivotallymounted thereon. This support is an elongated mounting at the ends ofwhich spaced rollers 50 are rotatably positioned. The ends of cable 40are also attached to each end for pulling the support 54 up or downalong the roller tracks. This movement of support 54 along the tracks 82upwardly (see FIG. 4) initially applies a compression force on push-pullrod 66 until pivot shaft 44, and door 24, swings outwardly. Thereafterthe continued upward pull on the bellcrank provides a tension on thepushpull rod, causing the lower bellcrank to drive the lower end of thedoor inwardly and upwardly.

As shown in FIG. 7 lower bellcrank 64 is mounted on the end of shaft 46and has a short arm 68 to which the lower end of push-pull rod 66 ispivotally attached. The longer arm 84 terminates in an integral crossbar86 to form a T-bogie" having rollers 74 mounted at each end. ThisT-bogie provides a camming action on the tracks which by analogy may becompared to that of a carpenter's crowbar. The cooperation of the curvedlower portion 80 of track 82 in FIG. 4 with the rollers 74 on each endof crossbar 86 is such that compression on push-pull rod 66' causes thelower portion of the door to move inwardly and subsequent tension on therod 66 pulls the lower part of the door upwardly.

In the embodiment shown in FIG. 5 the sequence of application ofcompression-tension forces is reversed because the direction of theshort arms of the bellcranks point inwardly of the fuselage from theirpivot points on the door instead of outwardly as shown in FIG. 4. Whenthe door is raised from closed position the upward pull on arm 52 ofbellcrank 48 places tension on push-pull rod 66 and lifting force on theshort arm 68 of the lower bellcrank. The relationship of the long arms70 with rollers 74 with the curvature of the lower end 80 of track 82 issuch that the lower end of the door swings inwardly and upwardly,converting the tension on push-pull rod 66 into compression, moving thetop of the door inwardly and upwardly.

Although the lower bellcrank shown in FIG. 4 and FIG. 7 may be used inthe embodiment shown in FIG. 5, the bellcrank shown in FIG. 8 isconsidered to be an improvement in its operation. Here the short arm 68,to which push-pull rod 66 is attached, is mounted on the lower doorpivot shaft 46. A pair of diverging long arms 70 are also affixed toshaft 46. The outer ends 88, 90 are connected by crossmember 92 forstructural support. Roller supports 72 are pivotally mounted to the ends88 and 90 of arms 70. A pair of rollers are mounted on each end of eachsupport 72. In this configuration the crossmember 92 compares with thecrossbar 86 in FIG. 7 and each roller support 72 with its four wheels 74replaces each pair of rollers in FIG. 7. This results in a smootherjamproof operation and, accordingly, is preferred to the bellcrank inFIG. 7

for use in both embodiments in FIGS. 4 and 5.

A sectional view of track 82 may be seen in FIG. 8. This track consistsof a U-shaped channel with intumed lips 94 between which roller supports72 may pass. The outer rollers 74 fit within the slot recess 96 are areprevented from having lateral movement therewith. Shafts 98 and 100 areconstructed so as to permit lateral movement between the bellcrank arms70 and the rollers 74. This compensates for slight lateral misalignmentof the tracks on the door jamb on installation. Track 82 also has agrooved portion 102 in which cable 40 may be carried.

In FIG. 9 there is shown the power apparatus for moving the door. Motor36 rotates shaft 38 on which is mounted a drive gear 102. A power pulleydrum 60 has a ear 104 connected to gear 102 by a drive chain 106.Counter alance spring 42 is mounted over spring drum 108 with end 110fastened thereto by pin 112. The other end 114 is attached to rotatableplate 116 by pin 118 which is adapted to rotate with power pulley 60through shaft 120. As the door is moved down to closed position thespring 42 tightens up so that it may assist in raising the door whensuch action is desired.

Having thus described the foregoing embodiments, modifications willreadily occur to those skilled in the art and it is to be understoodthat such modifications also are to be considered as part of thisinvention.

We claim:

1. An overhead plug door comprising:

a door with top and bottom laterally extending rotatable shafts thereon,bellcranks on each of said shafts,

said bellcranks on each shaft having arms thereon interconnected with, apush-pull rod whereby rotational movement of one bellcrank and shaftcauses rotational movement of the other bellcrank and shaft,

said bellcranks having other arms with spaced apart rollers thereon,

door jamb tracks engageable with said rollers,

said tracks having a nonconstant curvature whereby movement of saidrollers along said track rotates said bellcranks and said shafts andhence the roller position on said track determines the position of saiddoor relative to said tracks,

said rollers on said bellcranks on said top shafts being pivotallyconnected thereto and said rollers on said bellcranks on said bottomshafts being fixedly mounted thereon, and

lifting means secured to said upper rollers at points offset from theplane of said door in the closed position thereof, said upper bellcrankspivoting said door toward an in-line position with said upper rollerswhen a lifting force is exerted by said lifting means, whereby pivotingof said upper bellcrank causes said fixedly mounted rollers at thebottom of said door to react with said tracks to move the bottom of saiddoor relative to said tracks.

2. An overhead plug door as set forth in claim 1 wherein said tracks arecurved near the bottoms thereof to move said door into and out of adoorway opening between said tracks.

3. An overhead plug door as set forth in claim 1 wherein said tracksguide movement of said door between closed position within an openingdefined by said door jamb and an open position overhead.

4. An overhead plug door as set forth in claim 1 wherein a force appliedto an arm of one of said bellcranks along said tracks imparts arotational movement on said bellcrank and associated movement of thatportion of said door to which said bellcrank is pivotally mounted,

said push-pull rod imparting a similar movement to the other of saidbellcranks to move that portion of said door to which said otherbellcrank is associated, said push-pull rod responding to movement ofsaid other bellcrank to further rotate the first of said bellcranks. 5.An overhead plug door as set forth in claim'l wherein at least one ofsaid bellcranks has an arm with an integral crossbar with rollersmounted on the ends thereof.

6. An overhead plug door as set forth in claim 1 wherein at least one ofsaid bellcranks has an arm with a roller support pivotally mountedthereon.

7. An overhead plug door as set forth in claim 1 wherein at least one ofsaid bellcranks includes a pair of interconnected arms, each of whichhas rollers mounted thereon.

8. An overhead plug door as set forth in claim 7 wherein each of saidarms has a roller support pivotally mounted thereon with rollersmounted'at each end of said roller support.

1. An overhead plug door comprising: a door with top and bottomlaterally extending rotatable shafts thereon, bellcranks on each of saidshafts, said bellcranks on each shaft having arms thereon interconnectedwith a push-pull rod whereby rotational movement of one bellcrank andshaft causes rotational movement of the other bellcrank and shaft, saidbellcranks having other arms with spaced apart rollers thereon, doorjamb tracks engageable with said rollers, said tracks having anonconstant curvature whereby movement of said rollers along said trackrotates said bellcranks and said shafts and hence the roller position onsaid track determines the position of said door relative to said tracks,said rollers on said bellcranks on said top shafts being pivotallyconnected thereto and said rollers on said bellcranks on said bottomshafts being fixedly mounted thereon, and lifting means secured to saidupper rollers at points offset from the plane of said door in the closedposition thereof, said upper bellcranks pivoting said door toward anin-line position with said upper rollers when a lifting force is exertedby said lifting means, whereby pivoting of said upper bellcrank causessaid fixedly mounted rollers at the bottom of said door to react withsaid tracks to move the bottom of said door relative to said tracks. 2.An overhead plug door as set forth in claim 1 wherein said tracks arecurved near the bottoms thereof to move said door into and out of adoorway opening between said tracks.
 3. An overhead plug door as setforth in claim 1 wherein said tracks guide movement of said door betweenclosed position within an opening defined by said door jamb and an openposition overhead.
 4. An overhead plug door as set forth in claim 1wherein a force applied to an arm of one of said bellcranks along saidtracks imparts a rotational movement on said bellcrank and associatedmovement of that portion of said door to which said bellcrank ispivotally mounted, said push-pull rod imparting a similar movement tothe other of said bellcranks to move that portion of said door to whichsaid other bellcrank is associated, said push-pull rod responding tomovement of said other bellcrank to further rotAte the first of saidbellcranks.
 5. An overhead plug door as set forth in claim 1 wherein atleast one of said bellcranks has an arm with an integral crossbar withrollers mounted on the ends thereof.
 6. An overhead plug door as setforth in claim 1 wherein at least one of said bellcranks has an arm witha roller support pivotally mounted thereon.
 7. An overhead plug door asset forth in claim 1 wherein at least one of said bellcranks includes apair of interconnected arms, each of which has rollers mounted thereon.8. An overhead plug door as set forth in claim 7 wherein each of saidarms has a roller support pivotally mounted thereon with rollers mountedat each end of said roller support.